Many commercial and residential buildings are equipped with systems to receive natural or liquid petroleum gas to power various functions in the building such as heat or other appliances. These systems typically comprise an inlet gas line which provides gas from some remote source, a gas meter which may be coupled to the inlet gas line and which records how much gas is used in the building, and an outlet gas line which extends from the meter and into the building to feed other gas lines for various locations in the building. Such systems are also typically used to deliver other gases or liquids such as water to the building, as well as to record the amount of such gas or liquid used.
Should the system which delivers gas or liquid to the building be disrupted, leaks could occur which may lead to explosion, fire, flooding or other potentially disastrous situations. Such a disruption could result from earthquakes which are quite common in California and other earthquake-prone locations, or from an accident where a vehicle crashes into the building or the gas or liquid delivery system itself. To protect against potential leaks that could arise from such disruption, safety valves have been proposed which serve to seal off or close a gas line upon the occurrence of a disruption.
However, certain existing safety valves have one or more shortcomings which may limit their usefulness. For example, certain existing valves require various attachment means to integrate the valves into the existing gas or liquid delivery system. This generally increases the complexity and cost of providing a safety valve feature in the first place and reduces the ability for the valve to be retrofitted into existing systems. As another example, other existing valves require various internal components, such as electronic or pressure differential sensors, that may again increase the cost and complexity of the valve and reduce its reliability.
Furthermore, other existing safety valves are designed to be mounted externally to the gas meter such as on or in the gas lines extending to or from the meter. Where valves are placed external to the meter, permits or other approval from local governing or other regulatory agencies are typically required which itself is a time-consuming, expensive process. Also, such external placement may lead to inadvertent closing of the valve such as that which might occur if a child playing near the gas line bumps it. And because such safety valves would not typically be suitable to be retrofitted into the gas meter itself, this could well lead to the scrapping of gas meters, an environmentally undesirable result.
Accordingly, there is a need for a safety valve that is of simple design to increase its reliability and lower its cost thereby providing an incentive for using the valve in the first place. There is also a need for a safety valve which may be retrofitted into existing gas or liquid meters to reduce the risk of inadvertent use and maximize reliability.